Grades of Hypertension
According to the European Society of Cardiology/European Society of Hypertension (ESC/ESH) guidelines, hypertension is classified into three grades: Grade 1 (140-159/90-99 mmHg), Grade 2 (160-179/100-109 mmHg), and Grade 3 (≥180/≥110 mmHg). 1
European Classification System
The ESC/ESH classification system provides a comprehensive categorization of blood pressure levels:
- Optimal: <120/80 mmHg
- Normal: 120-129/80-84 mmHg
- High normal: 130-139/85-89 mmHg
- Grade 1 hypertension: 140-159/90-99 mmHg
- Grade 2 hypertension: 160-179/100-109 mmHg
- Grade 3 hypertension: ≥180/≥110 mmHg
- Isolated systolic hypertension: ≥140/<90 mmHg 1
Isolated systolic hypertension is further graded (1,2, or 3) according to the systolic blood pressure values in the ranges indicated, provided that diastolic values are <90 mmHg.
American Classification System
It's important to note that the American College of Cardiology/American Heart Association (ACC/AHA) uses a different classification system with lower thresholds:
- Normal: <120/<80 mmHg
- Elevated: 120-129/<80 mmHg
- Hypertension, stage 1: 130-139/80-89 mmHg
- Hypertension, stage 2: ≥140/≥90 mmHg 1
Clinical Implications
The classification of hypertension has significant implications for:
Risk assessment: Higher grades of hypertension correlate with increased cardiovascular risk. Even BP values in the 130-139/85-89 mmHg range are associated with a >2-fold increase in relative risk from cardiovascular disease compared to those with BP below 120/80 mmHg 1.
Treatment decisions: The threshold for pharmacological treatment depends not only on BP level but also on total cardiovascular risk, including:
- Presence of established cardiovascular disease
- Co-existence of other cardiovascular risk factors
- Presence of subclinical cardiovascular disease or end-organ damage 1
Target organ damage: Higher grades of hypertension increase the risk of damage to the heart, kidneys, brain, and blood vessels.
Important Clinical Considerations
When classifying a patient's hypertension:
- When systolic and diastolic blood pressures fall into different categories, the higher category should be applied 1.
- Multiple readings should be taken for accurate classification, with the ESC/ESH recommending 3 readings for office BP measurement 1.
- Out-of-office BP measurements (home or ambulatory monitoring) should be used to confirm office hypertension and identify white coat or masked hypertension 1.
Prevalence and Impact
The prevalence of hypertension varies by classification system. Using the ACC/AHA criteria (≥130/80 mmHg), approximately 46% of US adults have hypertension, compared to 32% using the traditional definition of ≥140/90 mmHg 1.
This classification system is crucial for clinical decision-making as it guides screening, diagnosis, and treatment approaches to reduce morbidity and mortality from hypertension-related cardiovascular events.